Blizzard has added a lot of new voice acted emotes into the game with 7.0. Some are currently broken implying its a work in progress. The dialogue spoken is dependent on your race and rarely gender. Here's what they say.
Every race
/forthealliance "For the Alliance!"
/forthehorde "For the Horde!"
Human
/doom "I'm going to hurt you a lot!"
/whoa "You don't see that every day..."
/taunt "Face me, coward!"
/sorry "Sorry about all this..."
Dwarf
/doom "I'm gonna rough ya up!"
/whoa "By Muradin's beard!"
/taunt "Yer moms a bearded Ogre and yer fathers a Trogg!"
/sorry "I'm sorry!"
Night Elves (currently /doom and /taunt are the same for males)
/doom "You came here to die..."
/taunt "You lack manners, maybe I can teach you some..."
/whoa "By Elune's grace!"
/sorry "hmm, my apologies"
Gnome
/doom "Get ready to die, simpleton!"
/whoa "ZOINKS! Did you see that?"
/taunt "I've taken on uglier and dumber than you! ...But not many"
Draenei
/doom "You will fall by my hand!"
/whoa "by the light of the Naaru!"
/taunt "You are no match for me!"
/sorry "my sincere apologies"
Worgen
/doom "You are in for a world of pain!"
/whoa "I don't believe it!"
/taunt "A bloody coward is what you are"
/sorry "Terribly sorry"
Pandaren (separate male and female /sorry)
/doom "I will help you find inner peace, but it's going to hurt!"
/whoa "By the Four Winds!"
/taunt "You're not afraid of a fair fight... are you?
/sorry (female)"I am very sorry"
/sorry (male) "Duìbùqǐ" (chinese for "I am sorry")
Orc
/doom "I will destroy you!"
/whoa "THRALL's BALLS!" (Literally best feature of the expansion)
/taunt "You have no honor, maggot!"
/sorry "That was my fault"
Undead
/doom "You're about to be dead... REAL DEAD!"
/whoa "By the Dark Lady!"
/taunt "You smell worse than my grave ever did"
/sorry "sorry... Get over it!"
Tauren
/doom "I will crush you like the vermin you are!"
/whoa "By the Earth mother!"
/taunt "You are without courage... fight me!"
/sorry "It was my mistake, apologies"
Troll
/doom *maniacal laughter* "I'm gonna enjoy hurtin' you!"
/whoa "Whoa! Did ya see that mon?"
/taunt "Come back when ya not so scared!"
/sorry "Oops, my bad, my bad"
Blood Elf
/doom "I will end you!"
/whoa "By the Sunwell!"
/taunt "You're not worth my time"
/sorry "sorry that happened"
Goblin (Goblin females have a separate /taunt)
/doom "Oh, you're gonna pay for this... with interest!"
/whoa "You seein' this? I don't believe it!"
/taunt "Oh, huh, think ya real tough pal? Forget you maggot!
/taunt (female) "Angels with dirty faces huh? heh heh heh"
/sorry "Whaddaya want an apology? fine, sorry"